The tachistoscopic recognition of letters under whole and partial report procedures as related to intelligence

Investigations of the short-term memory task performance of retarded individuals have indicated that these individuals demonstrate a deficit in the mechanisms necessary for the acquisition, storage and/or retrieval of information. The present study examined the tachistoscopic letter recognition task performance of retarded and non-retarded individuals under a partial report and a whole report procedure. The results revealed that the retarded subjects did significantly more poorly relative to the non-retarded subjects under both procedures. The data were interpreted as indicating that the retarded subjects were inefficient in their strategy to make the simultaneous imput task manageable. Further, the data provided no support for the suggestion that a visual-to-auditory encoding process exists between iconic and short-term memory.     

Availability and accessibility of information in the semantic memory of retarded and nonretarded adolescents

The availability of semantic information in storage and the accessibility of that information for retrieval were studied in retarded and nonretarded adolescents. In Experiment 1, 40 normal and 40 CA-equivalent (mean, 15 years) retarded subjects were required to retrieve information from semantic categories as well as to judge whether specific items were members of a given category. The results showed large IQ group differences on the retrieval task which could not be wholly accounted for by the items available in storage. Experiment 2 was designed as an attempt to remediate this retrieval deficit by introducing an organized retrieval plan consisting of subcategory cues. This organization facilitated retrieval as long as it was experimentally provided. Retrieval returned to its original level, however, when the cues were withdrawn. It was concluded that retarded persons had an accessibility deficit in addition to an availability deficit; one aspect of this accessibility deficit involved the failure to use spontaneously mnemonic strategies that were consistent with the semantic organization.     

Encoding and retrieval processes in normal children and retarded adolescents

Information processing capabilities of normal and retarded individuals were studied within the context of a modified Sternberg recognition memory task. Presentation of items in the memory set was self-paced, and stimulus exposure times and response latencies were recorded.It was found that normal and retarded individuals spent the same amount of time processing subspan lists during input to the memory system; however, the normal subjects spent less time retrieving information from that system than did the retarded subjects. Part of the superiority of normal subjects was attributable to their higher scanning speeds during the stimulus comparison stage of memory retrieval. The scanning strategy of normal and retarded subjects, on the other hand, was found to be the same: serial and exhaustive. It was further demonstrated that the binary decision stage of retrieval was not related to differences in intelligence.     

Phonological deficits: Beneath the surface of reading-acquisition problems

Summary In Experiment 1, the performance of young retarded readers on speech-segmentation tasks was compared with the performance of normal subjects matched for chronological age (CA) and with subjects matched for reading age (RA). Retarded readers were poorer than both control groups in consonant deletion, while there was no difference between the groups on a rhyme-judgement task and a syllabic-vowel-reproduction task. In Experiment 2, another group of reading retarded children was compared with CA and RA controls on the classification of pseudowords, either by common phoneme or by overall phonetic similarity. The retarded readers made fewer classifications based on common phoneme than both control groups, while there was no difference between the groups in classifications based on overall phonetic similarity. In Experiment 3, adult developmental dyslexics were compared with normal adults in the tasks of Experiments 1 and 2. The dyslexics made fewer classifications based on a common phoneme than the normals, while no difference was found in classifications based on overall phonetic similarity.     

Memory for objects in real scenes: The development of recognition and recall

Subjects examined crowded semirealistic layouts of toy objects, or photographs of these layouts, and then tried to identify added, moved or deleted items. The main study, involving 1st-, 3rd, 6th-graders, and adults, showed that although successful recognition of added items was superior to both recall of deleted items and recognition of moved ones, all three scores improved with age. In addition, false reports of “new” items decreased markedly in the older groups. The results argue against the widely held view that recognition memory undergoes little or no developmental improvement. No significant difference between real layouts and photographs appeared either in the main experiment or in replications involving shorter exposure (Experiment 2) or retarded subjects (Experiment 3).     

Motion information in iconic memory

Motion perception was investigated in two experiments using Sperling's partial report procedure. In Experiment 1, subjects were presented with 8 moving squares; at array offset an arrow cued subjects to locate all squares moving in the direction of the arrow. The partial report was found to be superior to the whole report and this was taken as evidence for the existence, in iconic memory, of information about the direction of motion. The second experiment revealed only a minor decay in this superiority with the indicator delayed up to 1 sec. The importance of optical transformations in vision was stressed and it was argued that information processing models need pay greater attention to them.     

The processing of multidimensional information from iconic storage: perceptual independence and comparative rates of decay

Using selection by location, the probe technique was applied to alphabetic and 2-dimensional position information. The purpose was to examine (a) the nature of iconic decay, and (b) whether, or not, both types of information are processed independently, when processed simultaneously. Positioning performance gained more benefit from partial report than identify performance, but decay rates were the same for both types of information. Data indicated the existence of perceptual interaction, but no response interaction, when both types of information were processed jointly. The perceptual interaction was attributed to an inverse relationship between structural stimulus complexity and clarity of iconic storage.     

The perception of complex patterns by touch

Two experiments are reported on matching Braille characters in dot pattern and outline shape formats by congenitally blind subjects. In a third experiment subjects' drawings of Braille shapes were analysed. Experiment 1 showed that normal and retarded readers differed significantly when outline shapes 'cued' identical dot patterns, but did not differ when the dot patterns preceded outlines. However, normal as well as retarded readers were faster and more accurate in judging identical pairs in dot-pattern format than in any other condition. In experiment 2 dot patterns and outline shapes were matched at three levels of reading proficiency. Faster readers made fewer errors in matching identical pairs, but all subjects were more accurate and faster with dot patterns than with outline shapes. Experiment 3 showed that blind subjects' drawing of outline shapes is not affected by reading proficiency. Most common were errors of alignment, including 'rotation' from vertical to horizontal axes, suggesting that sources of confusion were spatial position of dots and major axes of alignment rather than mirror-image reversals. It is argued that the results are not compatible with the hypothesis that Braille letters are perceived as global outline shapes by faster readers.     

Visual attribute modulates the time course of iconic memory decay

Studies on iconic memory demonstrate that rich information from a visual scene quickly becomes unavailable with the passage of time. The decay rate of iconic memory refers to the dynamics of memory availability. The present study investigated the iconic memory decay of different stimulus attributes that comprised an object. Specifically, in Experiment 1, participants were presented with eight coloured numbers (e.g., red 4) and required to remember only one attribute, either colour or number, over different blocks of trials. The participants then reported the cued attribute in which the cue Stimulus Onset Asynchrony (SOA) from the memory array onset was varied (0, 100, 200, 300, 500, and 1000?ms). We found that numerical information became unavailable more quickly than colour information, despite the fact that the memory accuracies at 0 and 1000?ms SOAs were comparable between the two attributes. In Experiment 2, we replicated the finding that a numerical representation was lost more quickly than a colour representation when visual masks followed the target stimulus. These results suggest that the various visual attributes comprising an object are lost over time at different rates in iconic memory. We discuss this finding in relation to how perceptual representation is transferred to the capacity-limited visual working memory.     

Read-out of emotional information from iconic memory: the longevity of threatening stimuli

Previous research has shown that emotional stimuli are more likely than neutral stimuli to be selected by attention, indicating that the processing of emotional information is prioritized. In this study, we examined whether the emotional significance of stimuli influences visual processing already at the level of transient storage of incoming information in iconic memory, before attentional selection takes place. We used a typical iconic memory task in which the delay of a poststimulus cue, indicating which of several visual stimuli has to be reported, was varied. Performance decreased rapidly with increasing cue delay, reflecting the fast decay of information stored in iconic memory. However, although neutral stimulus information and emotional stimulus information were initially equally likely to enter iconic memory, the subsequent decay of the initially stored information was slowed for threatening stimuli, a result indicating that fear-relevant information has prolonged availability for read-out from iconic memory. This finding provides the first evidence that emotional significance already facilitates stimulus processing at the stage of iconic memory.     

Misled subjects may know more than their performance implies

Many studies have demonstrated that subjects exposed to misleading postevent information are likely to report the misinformation with confidence on subsequent tests of memory for the event. The purpose of the present studies was to determine whether subjects exposed to misleading postevent information come to believe they remember seeing the misinformation at the original event. A second question addressed by the present studies is whether exposure to misinformation reduces subjects' ability to remember the source of items they witnessed at the original event. In two experiments, subjects viewed a slide sequence depicting an event, were subsequently exposed to misleading information or neutral information about selected aspects of the event, and were later tested on their memory for the source of original and misleading details. The results showed that exposure to misinformation did not lead subjects to believe they remembered seeing the misinformation, nor did it reduce subjects' ability to accurately identify the source of originally seen details. The same pattern of results was obtained whether subjects were tested immediately (Experiment 1) or after a 1-day delay (Experiment 2). Collectively, the results suggest that subjects may report misinformation even if they know they do not remember seeing it.     

Choice in a self-control paradigm: Quantification of experience-based differences

Previous quantitative models of choice in a self-control paradigm (choice between a larger, more-delayed reinforcer and a smaller, less-delayed reinforcer) have not described individual differences. Two experiments are reported that provide additional quantitative data on experience-based differences in choice between reinforcers of varying sizes and delays. In Experiment 1, seven pigeons in a self-control paradigm were exposed to a fading procedure that increased choices of the larger, more-delayed reinforcer through gradually decreasing the delay to the smaller of two equally delayed reinforcers. Three control subjects, exposed to each of the small-reinforcer delays to which the experimental subjects were exposed, but for fewer sessions, demonstrated that lengthy exposure to each of the conditions in the fading procedure may be necessary in order for the increase to occur. In Experiment 2, pigeons with and without fading-procedure exposure chose between reinforcers of varying sizes and delays scheduled according to a concurrent variable-interval variable-interval schedule. In both experiments, pigeons with fading-procedure exposure were more sensitive to variations in reinforcer size than reinforcer delay when compared with pigeons without this exposure. The data were described by the generalized matching law when the relative size of its exponents, representing subjects' relative sensitivity to reinforcer size and delay, were grouped according to subjects' experience.     

The effects on induced passive rehearsal and the von Restorff phenomenon on the free recall of normals and retardates

Noninstitutionalized retardates and normal children of equal mental age (approximately 8 years) listened to 11 orders of 20 nouns with no instructions to overtly or covertly rehearse. All subjects were in each of three list conditions: (a) when all words were at the same decibel (dB) level, (b) when the 11th item was at a higher dB level, and (c) when the items were repeated at the same dB level using the rehearsal protocol of Rundus (1971). The normals' overall recall was superior to that of the retardates' recall. Repetition of items had no effect on the performance of either group except in the recency portion of the learning curve and on the initial trial for both groups and the fifth trial for the retarded group. The normal group was more susceptible to the yon Restorff effect than was the retarded group. These results were discussed in terms of the changing and different recall strategies of the two groups.     

Visual masking,mental age,and retardation

Performance of retarded subjects under both forward and backward masking was less accurate than either an equivalent chronological age or equivalent mental age group of normals. It was suggested that the iconic memory impairment of retarded subjects in attributable in part to mental retardation and not simply to low mental age.     

物体的空间关系对语义相关判断的影响

采取快速语义判断任务探讨物体空间关系对语义相关判断的影响。实验1考察词对呈现方式与其指称物空间次序经验的关系对语义相关判断的影响。结果表明,词对呈现位置与其指称物的一般空间次序经验一致时语义判断快。实验2探讨词对呈现方式与其指称物构成方式的关系对语义相关判断的影响。结果表明,词对呈现方式与其指称物的构成方式一致时语义判断快。研究结果支持了知觉符号理论。     

Temporal aspects of selective masking

In two experiments, rows of random letter sequences were presented for 100 ms and were patterned masked at varying delays after display offset. In Experiment I recall was probed by visual partial report cues, while auditory probes were employed in Experiment II. Compared to no-masking control conditions, the masking stimulus had a selective effect at the different positions of the rows. The masking stimulus produced the largest decrements in recall of letters from the centre positions of the displays but had a minimal effect on performance at either end of the rows. Furthermore, it was demonstrated that improvements in recall were limited to the centre positions of the rows at increased delays of mask. Subsidiary analyses revealed that processing of the end letters of the displays terminates shortly after display offset while processing of the centre letters continues for at least 500 ms. The results are consistent with the notion that processing of multi-letter arrays commences at the ends of the rows and that the selective masking effect reflects the order of processing of the contents of iconic memory. However, these results were evident only in Experiment II which employed auditory partial report cues. When the partial report cues were visual, there were no effects of masking and minimal increases in performance at increased delays of mask. The discrepant results of the two experiments are discussed in terms of process interruption caused by obligatory attention to the partial report cues.     

Iconic memory and central processing capacity

Three experiments were conducted to assess whether or not iconic memory is influenced by demands placed upon central processing capacity. In Experiment 1 S was required to store material in short-term memory while performing an iconic memory task. In Experiments 2 and 3 S performed an auditory classification task concurrently with iconic storage. The three experiments did not reveal any significant impairment of iconic memory as a function of performing a subsidiary task. Similarly, performance on the subsidiary tasks did not suffer as a result of the concurrent iconic memory task.     

Identification,localization, and “iconic memory”: An evaluation of the bar-probe task

The partial report tachistoscopic task has been used to define “iconic memory,” a labile image-like precategorical visual store. Six interrelated partial report studies are reported that challenge the construct. On each trial, subjects were shown an eight-letter pseudoword (representing one of four orders of approximation to English) and a bar probe indicating which letter to report. The probe was delayed systematically, and the experiments included both mask and no-mask conditions. All three variables-familiarity of the material, masking, and delay of the probe-affected accuracy of report. Delaying the probe, for example, reduced accuracy by increasing location errors. Delaying the mask increased accuracy by reducing both location and item errors, but it did not reduce the location errors until its effect on item errors had reached asymptote. Across the stimulus array, however, masking reduced accuracy at all delays by increasing location errors. Finally, the greater accuracy associated with higher orders of approximation to English was complemented by a decrease in item errors, but the familiarity factor had no effect on location errors. Taken together, even though the task has been used to define the idea, the results indicate that the bar-probe task cannot be explained in terms of a simple iconic memory concept. Instead of a simple image-like buffer, the explanation requires a feature buffer, an “intelligent” letter identification process, and a postidentification character buffer. Iconic memory is a construct that oversimplifies the information processing system used in the bar-probe task.     

Comprehension in "hyperlexic" readers

Mentally retarded children who can read aloud written words better than one would expect from their Mental Age are often called hyperlexic. The reading comprehension thought to be impaired in such children was investigated in four experiments. Mentally retarded advanced decoders, including autistic and nonautistic children, were compared with younger nonretarded children matched for Mental Age and Reading Age. Experiment 1 established that mildly mentally retarded readers could match sentences to pictures as well as could be expected from their verbal ability. This was the same whether they read the sentences or heard them. Experiment 2 demonstrated that only the more able retarded subjects, but not the less able ones, used sentence context in a normal way in order to pronounce homographs. Experiments 3 and 4 showed that these same more able children could extract meaning at both sentence and story level, and their performance was indistinguishable from that of normal controls. Hence, it is doubtful whether these advanced decoders should be called hyperlexic. In contrast, the readers of relatively low verbal ability performed much worse than their normal controls. Although they could be induced under certain conditions to read sentence-by-sentence rather than word-by-word, they did not do so spontaneously. Furthermore, they did not make use of already existing general knowledge in order to answer questions about the stories they had read. The ability to comprehend in terms of large units of meaning seems to be specifically impaired in these low verbal ability fluent readers. We suggest that it is this impairment that marks true hyperlexia. Since there were no differences between autistic and nonautistic readers on any of our tasks, we conclude that hyperlexia is not an autism-specific phenomenon.